1. Field of the Invention
The present invention relates to semi-active condensate and frost protection for heat pipe heat recovery units.
2. Description of the Prior Art
Heat pipes, which are used in heating and cooling applications in moderate and cold climates, are sometimes subject to the formation of frost. There have been several techniques which are directed to solving the frost formation problem. One technique utilizes externally powered electrical heaters which must be activated periodically to defrost the heat pipe units. In another technique, the heat pipe unit is periodically tilted in order to shut off heat transfer and, therefore, to permit warm air to defrost the heat pipes. While the latter system does not require external power for the heater, it does require power for tilting the heat recovery unit. A further technique reverses the heat pipes 180.degree. to reverse the unit's flow path of warm exhaust.
Other protective devices are directed to prevention of freezing, solidification and condensation of other fluids, whether gaseous or liquid, such as corrosive liquids.